Add failing test for issue #51.

Access denied should be true, now false. This reproduces the bug.
Access callback to only allow "administer site configuration" access.

Fixes #51
Merge branch 'feature/51-admin-access' into develop

* feature/51-admin-access:
  Access callback to only allow "administer site configuration" access.
  Add failing test for issue #51.
removing unused README
Merge branch 'release/7.x-2.x-alpha2' into 7.x-2.x

* release/7.x-2.x-alpha2:
  removing unused README
  Access callback to only allow "administer site configuration" access.
  Add failing test for issue #51.